Comments

Unless you have some shading issues where the panels are located Yes, series wire.When you say MPPT that brings up the question, Is your controller a true MPPT controller? There's a lot of bogus Chinese controllers that even have MPPT on the face of the controller. Here's an example of a fake.

There are so many knockoffs claiming to be MPPT controllers, some are actually MPPT, others are PWM masquerading as such, but are PWM with a high voltage threshold, please post some links to the controller you have, often more eyes looking can help determine what it is you have.